2-5写一个HelloWorld程序

Flutter upgrade:cmd控制台中运行Flutter upgrade，升级flutterSDK
Flutter doctor 查看flutterSDK版本
flutter中的快捷键
r：点击后热加载，直接查看预览效果
p：在虚拟机中显示网格
o：切换Android和iOS的预览模式
q：退出调试预览模式

//谷歌推出的扁平化样式 大气美观import 'package:flutter/material.dart';//入口文件void main() => runApp(MyApp());//定义MyApp函数 继承静态的组件class MyApp extends StatelessWidget {//  重写build方法  @override//  返回一个组件 传递一个上下文  Widget build(BuildContext context) {    return new MaterialApp(      title: "welcome to flutter",      home: new Scaffold(        appBar: new AppBar(          title: new Text("Hello Worldtitle"),        ),        body: new Center(          child: new Text("Hello Worldbody"),        ),      ),    );  }}

3-1节TextWidget文本组件

import 'package:flutter/material.dart';void main() => runApp(MyApp());//静态组建class MyApp extends StatelessWidget {  @override  Widget build(BuildContext context) {    return MaterialApp(      title: 'TextWidget',      home: Scaffold(        appBar: AppBar(title: Text('TextWidget')),        body: Center(            child: Text(          'Flutter一切皆组件。Flutter一切皆组件。Flutter一切皆组件。Flutter一切皆组件。Flutter一切皆组件。',//                居中对齐 left right start end(后两个工作不常用 和left right类似 运行效果差不多)          textAlign: TextAlign.center,//              最大行数          maxLines: 1,//              默认值 直接把文本截断//              overflow: TextOverflow.clip,//            超出省略号 fade不常用 逐行颜色透明度减淡          overflow: TextOverflow.ellipsis,          style: TextStyle(              fontSize: 25.0,              color: Color.fromARGB(255, 255, 150, 150),//                  下划线实线              decorationStyle: TextDecorationStyle.solid,              decoration: TextDecoration.underline),        )),      ),    );  }}

3-2节ContainerWidget容器组件-1

import 'package:flutter/material.dart';void main() => runApp(MyApp());//静态组建class MyApp extends StatelessWidget {  @override  Widget build(BuildContext context) {    return MaterialApp(      title: 'TextWidget',      home: Scaffold(        appBar: AppBar(title: Text('TextWidget')),        body: Center(            child: Container(          child: new Text(            'Hello Imooc',            style: TextStyle(fontSize: 40.0),          ),//          底部居左对齐 第一个值为垂直方向 第二个值为水平方向//          alignment: Alignment.bottomLeft,          //          垂直居中水平向左对齐          alignment: Alignment.centerLeft,//          宽高颜色          width: 500.0,          height: 400.0,          color: Colors.lightBlue,        )),      ),    );  }}

3-3节 ContainerWidget容器组件-2

import 'package:flutter/material.dart';void main() => runApp(MyApp());//静态组建class MyApp extends StatelessWidget {  @override  Widget build(BuildContext context) {    return MaterialApp(      title: 'TextWidget',      home: Scaffold(        appBar: AppBar(title: Text('TextWidget')),        body: Center(            child: Container(          child: new Text(            'Hello Imooc',            style: TextStyle(fontSize: 40.0),          ),          alignment: Alignment.bottomLeft,          width: 500.0,          height: 400.0,//              内边距20//              padding:const EdgeInsets.all(20.0),//            分别设置上下左右的边距          padding: const EdgeInsets.fromLTRB(10.0, 0, 0, 59.0),//              外边距          margin: const EdgeInsets.all(10.0),          decoration: new BoxDecoration(            gradient: const LinearGradient(                colors: [Colors.lightGreen, Colors.purple, Colors.amber]),          ),        )),      ),    );  }}